Characterization of Plant Epidermal Lens Effects by a Surface Replica Technique

Optical replicas of leaf surfaces were made for characterizingthe lens properties of individual epidermal cells. Using a dentallatex, moulds were made of leaf surfaces and subsequently usedto produce agarose replicas. The replicas focused light in amanner similar to intact epidermal cells and it was possibleto measure both focal lengths and intensifications within leafreplicas of Thermopsis montana, Mahonia repens, and Smilacinastellata which had epidermal cells of different diameter. Focallengths ranged from 74—130 µm which indicated thatlight was concentrated within the underlying photosynthetictissues of these leaves. Focal intensifications were measuredsensiometrically and were 1.5 for T. montana and 2-6 for theother species. These values compare favourably with calculatedfocal lengths and measurements taken from isolated epidermallayers. The results indicate that the epidermis can concentratelight within the leaf to amounts well in excess of ambient light.Furthermore, the replicas faithfully reproduced fine anatomicaldetails from a wide variety of leaves and they provide a non-destructiveway to reproduce surface characteristics for anatomical andphysiological studies.